The invention generally relates to a structure for mounting a positive crankcase ventilation valve (herein referred to as a “PCV” valve) to a cylinder head of an internal combustion engine, such as an engine for powering an automobile and/or any other vehicle engine. Further, the PCV valve may be mounted directly to an intake manifold of such an engine. Also, the PCV valve may direct and/or adjust flow of gas that may be recirculated from the engine and/or exhaust system of a vehicle, for example, back to the engine to enhance engine power delivery and efficiency.
FIG. 6 illustrates a known PCV valve mounting structure. As shown in FIG. 6, a blow-by gas passage 106 includes an upstream-side passage portion 108 and a downstream-side passage portion 112 formed in a cylinder head 102 and an intake manifold 104 of the engine, respectively. The upstream-side passage portion 108 and the downstream-side passage portion 112 of the blow-by gas passage 106 may communicate with each other when the cylinder head 102 and the intake manifold 104 come into contact. A PCV valve 100 is mounted within the upstream-side passage portion 108 and the downstream-side passage portion 112 to extend therebetween. In detail, the PCV valve 100 may adjust flow rate of blow-by gas flowing though the blow-by passage 106. A stepped recess portion 110, with a diameter larger than the downstream-side passage portion 112, is formed in the cylinder head 102 at an open end portion of the upstream-side passage portion 108.
The PCV valve 100 has a valve case 114, a valve member 116 positioned within and extending internally throughout the valve case 114 and a valve spring 118. The valve case 114 includes a main case portion 114a and a sub-case portion 114b, both main and sub case portions 114a and 114b being made of resin. The main case portion 114a and the sub-case portion 114b are joined to each other in the axial direction (i.e., the left-to-right direction in FIG. 6) to collectively define a gas passage 120. A valve seat 122 made of metal is held between a right side end portion of the main case portion 114a and a left side end portion of the sub-case portion 114b to be coaxial with both the main and sub-case portions 114a and 114b. The valve seat 122 has an annular plate shape with a metering hole 122a formed therein. The valve member 116 enters into the gas passage 120, so that a cross-sectional passage area (i.e. the open area) of the metering hole 122a of the valve seat 122 may be adjusted in response to the axial movement of the valve member 116. The valve spring 118 biases the valve member 116 in an upstream-side direction (i.e. toward the left in FIG. 6) with respect to the gas passage 120. The downstream-side end of the PCV valve 100 (i.e., the right-side end of the sub-case portion 114b in FIG. 6) is fitted into the open-ended portion of the downstream-side passage portion 112 of the intake manifold 104. The remaining portion of the sub-case portion 114b is fitted into the stepped recess portion 110 of the cylinder head 102, and the main case portion 114a is also fitted into the stepped portion 110. A metering space 124 is defined as the region between the inner circumferential surface of the metering hole 122a of the valve seat 122 and the outer circumferential surface (i.e. metering surface) of the valve member 116.
A first O-ring 126 seals the cylinder head 102 to the valve case 114 and may fit into a corresponding first O-ring groove (not shown in FIG. 6) in the main case portion 114a. Similarly, a second O-ring 128 seals the intake manifold 104 to the valve case 114 and may fit into corresponding second O-ring groove (not shown in FIG. 6) formed in the sub-case portion 114b. A gasket 130 is positioned between joint surfaces of the cylinder head 102 and the intake manifold 104 and is fitted into a corresponding gasket-receiving groove in the joint surface of the intake manifold 104.
U.S. Patent Application Publication No. US2011/0203559 (also published as Japanese Laid-Open Patent Publication No. 2011-169258) generally discloses a PCV mounting structure similar to that shown in FIG. 6.
In detail, the mounting structure shown in FIG. 6 involves two O-rings, i.e., the first O-ring 126 for sealing the cylinder head 102 to the valve case 114, and the second O-ring 128 for sealing the intake manifold 104 to the valve case 114 as described above. Such an arrangement may result in difficulty in mounting the O-ring 126 and the O-ring 128 to the main case portion 114a and the sub-case portion 114b, respectively. Further, the operations for forming the O-ring grooves in the main and sub-case portions 114a and 114b are relatively involved and/or time-consuming. Thus, such an arrangement as described above may lead to an increase in costs associated with manufacturing and/or maintaining, for example, the mounting structure.
In view of the challenges discussed above, there is a need in the art for a PCV valve mounting structure with fewer components needed for operation, thus also contributing to a commensurate reduction in production costs associated with such a PCV valve mounting structure.